This invention relates to multimode document handling apparatus and automatic reproducing apparatus containing such document handling apparatus. In particular, the present invention relates to document handling apparatus having capability of placing a document on an imaging platen for single copy copying, multicopy copying, stream feeding of original documents, as well as book copying capabilities.
In the electrostatographic reproducing apparatus commonly in use today, a photoconductive insulating member is typically charged to uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the usual document. Subsequently, the electrostatic latent image on the photoconductive insulating layer is made visible by developing the image with developing powder referred to in the art as toner. Most development systems employ development material which comprise both charged carrier particles and charged toner particles which tiboelectrically adhere to the carrier particles. During development, the toner particles are attracted from the carrier particles by the charged pattern of the image areas on the photoconductive insulating area to form a powder image on the photoconductor. This may subsequently be transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure.
While the processing of the electrostatic latent image on the photoconductive insulating layer may be the same for each copy produced, it is often desirable to have different capabilities in terms of copying different types of documents, such as sheets or books, of providing multicopies of documents or of being able to quickly provide a copy of a collated set. Many commercial machines provide multimode capability through the use of a moving document platen which is reciprocated back and forth across the imaging platen to make one or more multiple copies. Book copying capability is also available in such devices merely by placing a book on the moving platen. Moving platen machines suffer from the deficiency in that they are not capable of stream feeding documents and therefore an inordinate length of time is necessary to copy a multi page document, for example, since for each copy the platen must be manually loaded, transported back and forth across the imaging platen and the document manually removed before the next document may be placed on the platen. In addition, moving platen machines typically take up a relatively large floor area since the moving platen frequently extends beyond the frame of the machine. Furthermore, a safety hazzard may potentially arise with the moving platen machines since the platens are driven beyond the frame of the machine in that the operator or passerby may be struck by this moving apparatus.
Stationary platen moving optics machines are also available commercially. The Xerox 3100 family of products are exemplary. In the Xerox 3107, for example, a document may be fed to the stationary platen where it is scanned with a moving optical system. In small copiers moving optical systems are comparatively expensive and take up a relatively large volume of sapce, thereby increasing the perceived size of the machine. In addition, while the Xerox 3107 is capable of stream feeding, it is possible for the operator to place the second document in the document feeder too soon after the first document has been placed thereby overlapping the documents.